CN101634743A - Zoom lens, lens barrel and image pickup apparatus - Google Patents

Zoom lens, lens barrel and image pickup apparatus Download PDF

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Publication number
CN101634743A
CN101634743A CN200910164696A CN200910164696A CN101634743A CN 101634743 A CN101634743 A CN 101634743A CN 200910164696 A CN200910164696 A CN 200910164696A CN 200910164696 A CN200910164696 A CN 200910164696A CN 101634743 A CN101634743 A CN 101634743A
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China
Prior art keywords
lens
zoom
aperture
focal length
wide
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Granted
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CN200910164696A
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Chinese (zh)
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CN101634743B (en
Inventor
南条雄介
小山高志
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Sony Corp
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Sony Corp
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Priority to JP2008192364A priority Critical patent/JP2010032628A/en
Priority to JP192364/08 priority
Application filed by Sony Corp filed Critical Sony Corp
Publication of CN101634743A publication Critical patent/CN101634743A/en
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Publication of CN101634743B publication Critical patent/CN101634743B/en
Expired - Fee Related legal-status Critical Current
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/005Diaphragms
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B15/00Optical objectives with means for varying the magnification
    • G02B15/14Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
    • G02B15/144Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only
    • G02B15/1441Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive
    • G02B15/144113Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive arranged +-++

Abstract

The invention relates to a zoom lens, lens barrel and image pickup apparatus. Disclosed herein is a zoom lens, wherein a stop moves in an optical axis direction n in a phase of zooming; a position of the stop in a telephoto end is located on an object side with respect to a position of the stop in a wide-angle end; an opening size of the stop is controlled in conjunction with the zooming so that an open F number becomes approximately constant in a range from the wide-angle end to a specific intermediate focal length; the opening size of the stop is made approximately constant in a range from the specific intermediate focal length to the telephoto end so that the open F number is changed; and the specific intermediate focal length fulfills the following conditional expression (1), wide-angle end focal lengthx1.5<specific intermediate focal length<telephoto end focal length/1.4 . . . (1).

Description

Zoom lens, lens barrel and camera head
Technical field
The present invention relates to zoom lens (zoom lens), lens barrel and camera head, more particularly, relate to len changeable so-called zoom lens as digital single lens reflex camera, comprise the lens barrel of these zoom lens and comprise the camera head of this lens barrel.
Background technology
For example, the so-called standard zoom lens of digital single lens reflex camera roughly are divided into three types, i.e. high type, high magnification type and popular style.In this case, in high type standard zoom lens, in whole zoom area, brightness is F2.8, and zoom is about 3 times.In high magnification type standard zoom lens, the brightness of wide-angle side is about F3.5, and zoom is above 10 times.In addition, in popular standard zoom lens, the brightness of wide-angle side is in the scope of F2.8-F4, and the brightness of telescope end is in the scope of F4-F5.6, and zoom arrives in about 5 times scope at about 4 times.
In recent years, in these standard zoom lens of three types, especially, the situation of selling well rate of high magnification type standard zoom lens is increased.Yet, the demand of following this standard zoom lens is also being increased, these standard zoom lens are different from high magnification type standard zoom lens, and have both other brightness of high type level and about 4 times to about 5 times popular other zoom of level.
Now,, have in whole zoom area at the standard zoom lens under the situation of brightness of F2.8 for the structure that the refracting power of standard zoom lens is arranged, exist negative lens group in preceding type and positive lens groups in preceding type.In preceding type, first lens combination is a negative lens group in negative lens group.For example, negative lens group is disclosed at preceding type zoom lens in the Jap.P. 2000-221399 communique.In addition, in preceding type, first lens combination is a positive lens groups in positive lens groups.In Jap.P. 2005-181556 and the 2007-264381 communique positive lens groups is disclosed in preceding type.In high magnification type standard zoom lens or popular zoom lens, the zoom lens with four groups of formula structures have become main flow, arrange positive lens groups, negative lens group, positive lens groups and positive lens groups successively from object side in described four groups of formulas structure.
In addition, negative lens group all is configured to aperture is moved along with zoom operation at preceding type zoom lens at preceding type zoom lens and positive lens groups, thereby makes aperture be positioned at object side from wide-angle side when telescope end carries out zoom operation.
Therefore, in whole zoom area, when hope is definite value with brightness settings, when for example being set at F2.8 because from wide-angle side to the process of telescope end zoom, the position of emergent pupil keeps away port area, so must control like this, the distally becomes bigger so that the opening size of aperture is visible.
Yet when the opening size of aperture became big, the external diameter of part that is used to take in the aperture blades (vane) of iris apparatus became big, and the lens barrel that is used to hold aperture blades also becomes greatly, and this causes size to become problem big and that the weight change weighs.
In addition, aperture not only, and also the effective diameter that is arranged in the lens of image-side with respect to aperture also must be done greatly.Specifically, in the wide-angle side, with picture altitude be set on the occasion of and the amount of incident of last side beam when carrying out beam ray tracing increase, the result causes and is difficult to carry out the aberration correction.In this case, consider the refracting power of lens combination is died down to carry out the aberration correction.Yet, when the refracting power of lens combination dies down, the diameter of lens must be done greatly, this causes the size of zoom lens, lens barrel and camera head to become big.
In addition, in the disclosed popular zoom lens with about 5 times of zoom of Jap.P. 2007-264381 communique, open F value (open F number) is set at F3.5 in wide-angle side, and the remote setting that is visible is F4.5.Therefore, though in middle focal length, the open F value is considered to change to F4.5 gradually from F3.5, but in fact the open F value make zoom surpass 2 times near become about F4.5, the result causes the different specification of recognizing in some cases with the user of specification (specification).
Summary of the invention
Make the present invention in order to overcome the problems referred to above, therefore be desirable to provide a kind of zoom lens and comprise the lens barrel of these zoom lens and the camera head that comprises this lens barrel, in described zoom lens, zooming range and high magnificationization with constant open F value are compatible each other.
In order to reach above-mentioned purpose, according to an embodiment of the invention, provide a kind of zoom lens, wherein: aperture moves along optical axis direction in the zoom process; Described aperture is positioned at object side with respect to described aperture in the position of wide-angle side in the position of telescope end; Control the opening size of described aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from described wide-angle side to specific middle focal length; From described specific middle focal length in the scope of described telescope end, the opening size of described aperture is made approximate definite value, to change described open F value; And the described specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1).
Therefore, in these zoom lens, in the scope from wide-angle side to the specific middle focal length that satisfies above conditional (1), the open F value becomes approximate definite value.In addition, from this specific middle focal length in the scope of telescope end, the opening size of aperture is made approximate definite value, to change the open F value.
In above-mentioned zoom lens, preferably, in scope, make the open F value brighter than F3 from described wide-angle side to described specific middle focal length.
In scope, make the open F value brighter, can realize guaranteeing that brightness is approximate definite value in the scope from wide-angle side to specific middle focal length than F3 from wide-angle side to specific middle focal length.
Preferably, above-mentioned zoom lens are made of first lens combination of arranging successively from object side, second lens combination, the 3rd lens combination and the 4th lens combination, described first lens combination has positive refracting power, described second lens combination has negative refracting power, described the 3rd lens combination has positive refracting power and moves along optical axis direction integratedly with described aperture, and described the 4th lens combination has positive refracting power; When the side of looking in the distance from wide angle side is carried out zoom operation, interval between described first lens combination and described second lens combination increases, interval between described second lens combination and described the 3rd lens combination narrows down, and the interval between described the 3rd lens combination and described the 4th lens combination narrows down; In the focusing process, described second lens combination moves along optical axis direction; Zoom is set at 3.5 times or bigger.
By the way zoom lens are configured to positive lens groups in preceding type, can realize guaranteeing high variable power, and can reduce to be positioned at the external diameter of the lens of close object side of the length overall and first lens combination of wide-angle side.
In addition, preferably, described second lens combination has at least three concavees lens and a slice convex lens, and the concavees lens of close object side and at least one surface in the convex lens form aspheric surface.
Form aspheric surface by concavees lens and at least one surface in the convex lens with the object side of the most close second lens combination, can realize effectively utilizing aspheric surface, follow the wide-angleization of wide-angle side and the various aberrations that take place with correction, and the open F value of modifying factor telescope end brightens and the various aberrations that produce.
In addition, in above-mentioned zoom lens, preferably, constitute described first lens combination by arrange concavees lens, convex lens and male bend moon-shaped lens successively from object side; By arranging successively that from object side at least one surface forms aspheric recessed meniscus shaped lens, concavees lens, forms balsaming lens that aspheric convex lens form and the recessed meniscus shaped lens lens of concave surface directed towards object side constitute described second lens combination by the surface of concavees lens and image-side; Described aperture is arranged in the object side of described the 3rd lens combination; By arranging biconvex lens from object side successively and constituting described the 3rd lens combination by the balsaming lens that biconvex lens and concavees lens form; By arranging successively that from object side at least one surface forms aspheric biconvex lens, concave surface points to the recessed meniscus shaped lens of image-side and constitutes described the 4th lens combination by the balsaming lens that concavees lens and convex lens form.
Constitute zoom lens by the way, can guarantee high variable powerization and required open F value, and can revise various aberrations satisfactorily.
According to another embodiment of the present invention, a kind of lens barrel is provided, comprising: zoom lens; Portion is furnished with the lens holding cylinder of described zoom lens within it; Wherein, in described zoom lens: aperture moves along optical axis direction in the zoom process; Described aperture is positioned at object side with respect to described aperture in the position of wide-angle side in the position of telescope end; Control the opening size of described aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from described wide-angle side to specific middle focal length; From described specific middle focal length in the scope of described telescope end, the opening size of described aperture is made approximate definite value, to change described open F value; And the described specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1).
Therefore, in this lens barrel, in the scope from wide-angle side to the specific middle focal length that satisfies above conditional (1), the open F value becomes approximate definite value.In addition, from this specific middle focal length in the scope of telescope end, the opening size of aperture is made approximate definite value, to change the open F value.
According to an embodiment more of the present invention, a kind of camera head is provided, comprising: lens barrel, described lens barrel has zoom lens and lens holding cylinder, and described zoom lens are arranged in described lens holding cylinder inside; The optical imagery of described zoom lens formation is converted to the imaging apparatus of electric signal; With the device body that is used to keep described lens barrel; Wherein, in described zoom lens: aperture moves along optical axis direction in the zoom process; Described aperture is positioned at object side with respect to described aperture in the position of wide-angle side in the position of telescope end; Control the opening size of described aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from described wide-angle side to specific middle focal length; From described specific middle focal length in the scope of described telescope end, the opening size of described aperture is made approximate definite value, to change described open F value; And the described specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1).
Therefore, in this camera head, in the scope from wide-angle side to the specific middle focal length that satisfies above conditional (1), the open F value becomes approximate definite value.In addition, from this specific middle focal length in the scope of telescope end, the opening size of aperture is made approximate definite value, to change the open F value.
In zoom lens of the present invention: aperture moves along optical axis direction in the zoom process; Aperture is positioned at object side with respect to aperture in the position of wide-angle side in the position of telescope end; Control the opening size of aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from wide-angle side to specific middle focal length; In scope, the opening size of aperture is made approximate definite value, to change the open F value from specific middle focal length to telescope end; And the specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1).
Lens barrel of the present invention comprises zoom lens and lens holding cylinder, and described zoom lens are arranged in described lens holding cylinder inside, and wherein, in described zoom lens: aperture moves along optical axis direction in the zoom process; Aperture is positioned at object side with respect to aperture in the position of wide-angle side in the position of telescope end; Control the opening size of aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from wide-angle side to specific middle focal length; In scope, the opening size of aperture is made approximate definite value, to change the open F value from specific middle focal length to telescope end; And the specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1).
Camera head of the present invention comprises lens barrel, imaging apparatus and is used to keep the device body of lens barrel, described lens barrel has zoom lens and lens holding cylinder, described zoom lens are arranged in described lens holding cylinder inside, described imaging apparatus is used for converting the optical imagery that described zoom lens form to electric signal, wherein, in described zoom lens: aperture moves along optical axis direction in the zoom process; Aperture is positioned at object side with respect to aperture in the position of wide-angle side in the position of telescope end; Control the opening size of aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from wide-angle side to specific middle focal length; In scope, the opening size of aperture is made approximate definite value, to change the open F value from specific middle focal length to telescope end; And the specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1).
Therefore, at described zoom lens, comprise the lens barrel of described zoom lens and comprise in the camera head of described lens barrel, can make zoom area and high magnificationization compatible each other with constant bright open F value (bright open Fnumber).
Description of drawings
Figure 1A-1C illustrates the lens configuration of the zoom lens of one embodiment of the present invention respectively;
Fig. 2 is the aberration diagram of numerical value embodiment of the embodiment of the zoom lens shown in Figure 1A-1C, shows spherical aberration, astigmatism and distortion aberration under the wide-angle side state;
Fig. 3 is the aberration diagram of numerical value embodiment of the embodiment of the zoom lens shown in Figure 1A-1C, shows spherical aberration, astigmatism and distortion aberration under the specific middle focal length state;
Fig. 4 is the aberration diagram of numerical value embodiment of the embodiment of the zoom lens shown in Figure 1A-1C, shows spherical aberration, astigmatism and distortion aberration under the telescope end state;
Fig. 5 is the perspective schematic view of the camera head of one embodiment of the present invention;
Fig. 6 is a skeleton view, shows the structure of aperture control gear of the camera head of embodiment shown in Figure 5;
Fig. 7 is an enlarged perspective, shows the structure of installation unit of the camera head of embodiment shown in Figure 5;
Fig. 8 is an enlarged perspective, shows the structure of default ring of the camera head of embodiment shown in Figure 5;
Fig. 9 amplifies decomposition diagram, shows the structure of aperture unit of the camera head of embodiment shown in Figure 5.
Embodiment
Describe zoom lens of the present invention below with reference to the accompanying drawings in detail, comprise the lens barrel of these zoom lens and comprise the preferred implementation of the camera head of this lens barrel.
The embodiment pattern of zoom lens of the present invention is at first described.
The zoom lens of present embodiment pattern are constructed as follows.That is, aperture moves along optical axis direction in the zoom process; The aperture position of telescope end is positioned at object side with respect to the aperture position of wide-angle side; Control the opening size of aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from wide-angle side to specific middle focal length; In the scope from specific middle focal length to telescope end, the opening size of aperture is being made approximate definite value, to change the open F value; And the described specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1)
In these zoom lens, preferably, control the opening size of aperture in company with zoom operation, so that for example becoming in the scope from wide-angle side to specific middle focal length, the open F value falls into ± approximate definite value in 10% scope.
In addition, in these zoom lens, in the scope from specific middle focal length to telescope end, the opening size of aperture is for example made and is fallen into ± the interior approximate definite value of 10% scope, to change the open F value.
About above conditional (1),, make the control of the opening size of aperture is switched to the state of maximum gauge for approximate definite value from the open F value for the state of approximate definite value according to specific middle focal length.Following prescribing a time limit in exceeding (exceed) conditional (1), specification becomes the specification specification much at one with existing popular standard zoom lens.On the other hand, going up in limited time in exceeding conditional (1), aperture becomes excessive at the opening size of telescope end, and this causes size to become big and is difficult to revise aberration.
As mentioned above, in these zoom lens, the opening size of aperture changes with the zoom operation, so that the open F value becomes approximate definite value in the given area of wide-angle side.Therefore, can satisfy the so-called high type specification of the zoom of guaranteeing given bright open F value simultaneously and being scheduled to.
In addition, increase and the side of looking in the distance that causes the size of lens barrel to increase, the opening size of aperture is made approximate definite value, thereby can realize avoiding increasing the size of lens barrel at the opening size of aperture.In addition, because telescope end does not need bright open F value, become big in image-side with respect to aperture so prevented the effective diameter of lens.Thereby prevented that too much light quantity from unnecessarily inciding the wide-angle side, thereby can carry out gratifying aberration correction.
Therefore, in these zoom lens, can make zoom area and high magnificationization compatible each other with constant bright open F value.
Preferably, in these zoom lens, in scope, make the open F value brighter than F3 from wide-angle side to specific middle focal length.
Owing in from wide-angle side to specific middle focal length scope, make the open F value brighter, can obtain the specification identical in the wide-angle side with the specification of existing high type zoom lens than F3.That is to say,,, also can guarantee external diameter with existing popular zoom lens lens barrel much at one even then when telescope end is made the open F value approximate definite value if the open F value is darker than F3.Yet, in this case, may not obtain as the high type zoom lens of purpose of the present invention and the fusion between the popular zoom lens.
In addition, preferably, above-mentioned zoom lens are by first lens combination of arranging successively from object side, second lens combination, the 3rd lens combination and the 4th lens combination constitute, described first lens combination has positive refracting power, described second lens combination has negative refracting power, and described the 3rd lens combination has positive refracting power and moves along optical axis direction integratedly with aperture, and described the 4th lens combination has positive refracting power.In this case, preferably, when the side of looking in the distance from wide angle side was carried out zoom operation, the interval between first lens combination and second lens combination increased, interval between second lens combination and the 3rd lens combination narrows down, and the interval between the 3rd lens combination and the 4th lens combination narrows down.In addition, in the focusing process, second lens combination moves along optical axis direction, and zoom is set at 3.5 times or bigger.
Zoom lens are configured to positive lens in preceding type, even it is 3.5 times or when bigger that the result makes the angle of visibility when wide-angle side be set at 70 ° or bigger and zoom, also can make the external diameter of the length overall of wide-angle side and front lens (lens of the most close object side of first lens combination) relative less.Therefore, can obtain to be used to reach the optics refracting power configuration of purpose of the present invention.
In these zoom lens, preferably, second lens combination has at least three concavees lens and a slice convex lens, and the concavees lens of close object side and at least one surface of convex lens form aspheric surface.
Constitute zoom lens by the way, can realize effectively utilizing aspheric surface, follow the various aberrations of the wide-angleization of wide-angle side with correction, and the open F value of modifying factor telescope end brightens and the various aberrations that increase.In addition, in the concavees lens of the most close object side by aspheric surface being formed on second lens combination, can revise the variation of filed curvature effectively, the variation of this filed curvature is followed the focusing operation of wide-angle side and distortion aberration and is taken place.In addition, by aspheric surface being formed in the convex lens of second lens combination, can revise the focusing operation of following telescope end effectively and the coma aberration that takes place.
In addition, preferably construct these zoom lens in the following manner.That is, by arranging successively that from object side concavees lens, convex lens and male bend moon-shaped lens constitute first lens combination.By arranging successively that from object side following lens constitute second lens combination: at least one surface forms aspheric recessed meniscus shaped lens; Concavees lens; The surface of concavees lens and image-side forms the balsaming lens of aspheric convex lens; Recessed meniscus shaped lens with concave surface directed towards object side.Aperture is arranged in the object side of the 3rd lens combination, and constitutes the 3rd lens combination by the balsaming lens of arranging biconvex lens and biconvex lens and concavees lens from object side successively.In addition, by arranging successively that from object side at least one surface forms aspheric biconvex lens, concave surface points to the recessed meniscus shaped lens of image-side and constitutes the 4th lens combination by the balsaming lens that concavees lens and convex lens form.
Constitute zoom lens by the way, can satisfy angle of visibility in wide-angle side and be 80 ° or bigger, zoom and be about 5 times and be about from the zoom of wide-angle side that the open F value is the specification that definite value promptly is about F2.8 in 3 times the scope, and can revise various aberrations satisfactorily.
Describe the embodiment and the numerical value embodiment thereof of zoom lens of the present invention in detail below with reference to Fig. 1-4 and table 1-3.
It should be noted that the meaning of the quotation mark shown in below describing etc. is presented below.
" surface number i " is the sequence number from i surface of object side, " radius-of-curvature r " is from the radius-of-curvature of object side to i the surface (i surface) of image-side, and " spaced surface d " is the axle upper surface interval between i surface and (i+1) individual surface.In addition, " refractive index n d " constitutes the refractive index of the material of lens at d line (wavelength 587.6nm), and " Abbe number vd " constitutes the Abbe number of the material of lens at the d line.In addition, for surface number, the related surface of " ASP " expression forms aspheric surface; For radius-of-curvature, the related surface of " ∞ " expression is the plane; And for spaced surface, the related surface of " variable " expression presents variable interval.
Aspherical shape is defined by following formula (2):
x i=H 2/r i{1+(1-H 2/r i 2) 1/2}+∑A kH k...(2)
Wherein, x iBe the degree of depth of aspheric surface, H is the height from optical axis, r iBe radius-of-curvature, A kBe the aspheric surface coefficient, and k is progression (order).
Figure 1A-1C illustrates the lens arrangement of the zoom lens 1 of one embodiment of the present invention respectively.As can be known, zoom lens 1 have 15 lens from these figure.
Wherein, Figure 1A illustrates the wide-angle side state, and Figure 1B illustrates specific middle focal length state, and Fig. 1 C illustrates the telescope end state.
Constitute zoom lens 1 by the 4th lens combination 14 of arranging first lens combination 11, second lens combination 12 from object side successively, have the 3rd lens combination 13 of positive refracting power and having a positive refracting power with negative refracting power with positive refracting power.In this case, the 3rd lens combination 13 moves along optical axis direction integratedly with aperture 2.In addition, be arranged in the image-side of the 4th lens combination 14 as the image planes 3 of imaging moiety.
In zoom lens 1, when the side of looking in the distance from wide angle side is carried out zoom operation, interval between first lens combination 11 and second lens combination 12 increases, and the interval between second lens combination 12 and the 3rd lens combination 13 narrows down, and the interval between the 3rd lens combination 13 and the 4th lens combination 14 narrows down.In addition, when carrying out focusing operation, second lens combination 12 moves along optical axis direction.
In zoom lens 1, change the opening size of aperture 2, make the open F value be about 5 times and reach approximately from the wide-angle side zoom that to become definite value in 3 times the scope be F2.8 in zoom.In addition, making the opening size of aperture in zoom from about 3 times in the distolateral scope of looking in the distance is approximate definite value, thereby at telescope end the open F value is set at F3.5 approximately.
By arranging successively that from object side concavees lens 111, convex lens 112 and male bend moon-shaped lens 113 constitute first lens combination 11.
By arranging successively that from object side recessed meniscus shaped lens 121, concavees lens 122, balsaming lens and recessed meniscus shaped lens 125 constitute second lens combination 12.In this case, recessed meniscus shaped lens 121 is formed with compound aspheric surface on the surface of its object side.Described balsaming lens forms aspheric convex lens 124 gummeds by the surface of concavees lens 123 and image-side and forms.In addition, the concave surface directed towards object side of male bend moon-shaped lens 125.
By arranging successively that from object side biconvex lens 131 and the balsaming lens that is formed by biconvex lens 132 and concavees lens 133 gummeds constitute the 3rd lens combination 13.
By arranging successively that from object side biconvex lens 141, recessed meniscus shaped lens 142 and balsaming lens constitute the 4th lens combination 14.In this case, two of biconvex lens 141 surfaces all form aspheric surface.The concave surface of recessed meniscus shaped lens 142 points to image-side.In addition, described balsaming lens is formed by concavees lens 143 and convex lens 144 gummeds.
The aperture 2 that moves along optical axis direction integratedly with the 3rd lens combination 13 is arranged in the object side of the 3rd lens combination 13.
Table 1 illustrates the lens data among the numerical value embodiment of embodiment of zoom lens 1.
Table 1
Optical element Surface number i Radius-of-curvature r Spaced surface d Refractive index n d Abbe number vd
?111 ??1 ??124.181 ??3.000 ??1.92286 ??20.9
?112 ??2 ??58.560 ??7.320 ??1.77250 ??49.6
??3 ??222.222 ??0.150
?113 ??4 ??48.082 ??6.000 ??1.83481 ??42.7
??5 ??106.855 Variable
?121 ??6’(ASP) ??45.872 ??0.080 ??1.53610 ??41.2
?121 ??6 ??43.234 ??0.850 ??1.72916 ??54.7
??7 ??11.209 ??7.126
?122 ??8 ??-93.063 ??0.850 ??1.72916 ??54.7
??9 ??75.361 ??2.377
?123 ??10 ??-62.191 ??0.850 ??1.88300 ??40.8
?124 ??11 ??62.191 ??4.306 ??1.82114 ??24.1
??12(ASP) ??-29.119 ??1.043
?125 ??13 ??-16.529 ??0.850 ??1.77250 ??49.6
??14 ??-28.286 Variable
Aperture 2 ??15 ??∞ ??0.900
?131 ??16 ??71.058 ??3.122 ??1.58144 ??40.9
??17 ??-71.058 ??0.150
?132 ??18 ??33.024 ??6.625 ??1.48749 ??70.4
?133 ??19 ??-24.232 ??1.000 ??1.88300 ??40.8
??20 ??1148.600 Variable
?141 ??21(ASP) ??32.906 ??5.698 ??1.58313 ??59.5
??22(ASP) ??-32.906 ??1.205
?142 ??23 ??71.615 ??0.850 ??1.88300 ??40.8
??24 ??28.731 ??3.232
?143 ??25 ??116.000 ??0.850 ??1.90366 ??31.3
?144 ??26 ??28.023 ??6.312 ??1.51680 ??64.2
??27 ??-28.023 Variable
Imaging region 3 ??28 ??∞
In zoom lens 1, the recessed meniscus shaped lens 121 of second lens combination 12 respectively forms aspheric surface at the biconvex lens 141 of surface of object side (surface number 21) and the 4th lens combination 14 on the surface of image-side (surface number 22) at the biconvex lens 141 of the surface of image-side (surface number 12), the 4th lens combination 14 at the convex lens 124 of the surface of object side (surface number 6 '), second lens combination 12.
Table 2 illustrates aspheric level Four asphericity coefficient A4, six grades of asphericity coefficient A6 or the like among this numerical value embodiment.
It should be noted that in table 2, " E-i " is 10 being the exponential expression at the end, i.e. expression " 10 -i".For example, " 0.12345E-05 " expression " 0.12345 * 10 -5".
Table 2
Surface number ??6’ ??12 ??21 ??22
??A4 ??+0.70892e-05 ??-0.20260e-04 ??-0.14937e-04 ??+0.14937e-04
??A6 ??-0.74947e-07 ??-0.54576e-07 ??+0.19041e-07 ??-0.19041e-07
??A8 ??+0.10798e-08 ??-0.48087e-09 ??-0.23780e-10 ??+0.23780e-10
??A10 ??-0.11224e-10 ??-0.14600e-11
??A12 ??+0.65354e-13
??A14 ??-0.20000e-15
??A16 ??+0.25358e-18
Variable interval when table 3 illustrates lens position state variation among this numerical value embodiment and be in the open F value under wide-angle side state (focal distance f=16.492), specific middle focal length state (focal distance f=48.814) and the telescope end state (focal distance f=77.958), the opening size and angle of visibility 2 ω of aperture.
Table 3
Focal length ??16.492 ??48.814 ??77.968
The F value ??2.85 ??2.94 ??3.59
The opening size of aperture ??15.274 ??19.702 ??19.656
??2ω(°) ??83.54 ??32.30 ??20.50
??d5 ??1.740 ??28.004 ??33.036
??d14 ??19.485 ??6.079 ??1.000
??d20 ??6.070 ??1.402 ??0.600
??d27 ??37.034 ??55.441 ??72.072
Fig. 2-4 is respectively the various aberration diagrams under the focus for infinity state of this numerical value embodiment.Fig. 2 is the various aberration diagrams under the wide-angle side state (focal distance f=16.492), and Fig. 3 is the various aberration diagrams under the specific middle focal length state (focal distance f=48.814), and Fig. 4 is the various aberration diagrams under the telescope end state (focal distance f=77.968).
In the various aberration diagrams shown in Fig. 2-4, in the spherical aberration curve, solid line is represented the value of d line (wavelength is 587.6nm), and dotted line is represented the value of g line (wavelength is 435.8nm), and dash line is represented the value of c line (wavelength is 656.3nm).In addition, in the astigmatism curve, solid line is represented the value in the sagittal image surface (sagittal image surface), and dotted line is represented the value in the meridianal image surface (meridional imagesurface).
From the aberration diagram shown in Fig. 2-4 obviously as seen, in this numerical value embodiment, revised various aberrations satisfactorily, and zoom lens 1 has good imaging performance.
As mentioned above, in this numerical value embodiment, the wide-angle side focal length is 16.492, and specific middle focal length is 48.814, and the telescope end focal length is 77.968.
Therefore, the zoom lens of this numerical value embodiment are configured to make specific middle focal length to satisfy following passing through the inequality expression formula that obtains in the above-mentioned conditional of above value substitution (1):
16.492×1.5<48.814<77.968/1.4
Note that above-mentioned embodiment and numerical value embodiment thereof just reach an example of purpose of the present invention.That is to say that the lens element that constitutes the balsaming lens of each among second to the 4th lens combination 12-14 can be arranged apart from each other.On the contrary, lens element arranged apart from each other can be configured to the form of balsaming lens.
The embodiment pattern of lens barrel of the present invention is described below.
The lens barrel of present embodiment pattern comprises zoom lens and lens holding cylinder, and described zoom lens are arranged in described lens holding cylinder inside.
Zoom lens in the lens barrel of present embodiment pattern are constructed as follows.That is, aperture moves along optical axis direction in the zoom process; Aperture is positioned at object side with respect to aperture in the position of wide-angle side in the position of telescope end; Control the opening size of aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from wide-angle side to specific middle focal length; In scope, the opening size of aperture is made approximate definite value, to change the open F value from specific middle focal length to telescope end; And the specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1)
In this lens barrel, preferably, preferably control the opening size of aperture in company with zoom operation, so that for example becoming in the scope from wide-angle side to specific middle focal length, the open F value falls into ± approximate definite value in 10% scope.
In addition, in this lens barrel, preferably, in scope, the opening size of aperture for example made fall into ± approximate definite value in 10% scope, to change the open F value from specific middle focal length to telescope end.
For above conditional (1),, make the control of the opening size of aperture is switched to the state of maximum gauge for approximate definite value from the open F value for the state of approximate definite value according to specific middle focal length.When exceeding down in limited time, specification becomes the specification specification much at one with existing popular standard zoom lens.On the other hand, when exceeding in limited time, aperture becomes excessive at the opening size of telescope end, and this causes size to become big and is difficult to revise aberration.
As mentioned above, in this lens barrel, the opening size of aperture changes in company with zoom operation, so that the open F value becomes approximate definite value in the given area of wide-angle side.Therefore, can satisfy the so-called high type specification of the zoom of guaranteeing given bright open F value simultaneously and being scheduled to.
In addition, increase and the side of looking in the distance that causes the size of lens barrel to increase, the opening size of aperture is made approximate definite value, thereby can realize avoiding increasing the size of lens barrel at the opening size of aperture.In addition, because telescope end does not need bright open F value, become big in image-side with respect to aperture so prevented the effective diameter of lens.Thereby prevented that too much light quantity from unnecessarily inciding the wide-angle side, thereby can carry out gratifying aberration correction.
Therefore, in this lens barrel, can make zoom area and high magnificationization compatible each other with constant bright open F value.
Embodiment according to lens barrel of the present invention will be described below.
Lens barrel 22 (with reference to figure 5) comprises zoom lens 1 and lens holding cylinder (with reference to figure 5), and described zoom lens 1 are arranged in the described lens holding cylinder 23.Zoom lens 1 shown in Figure 1 are installed in the lens barrel 22, identical with reference to figure 1 description of installing mode and structure thereof.In addition, lens holding cylinder 23 camera head 20 (with reference to figure 5) of packing into, and describe in the embodiment of its structure and camera head 20 (aftermentioned) identical.
The embodiment pattern of various details camera head.
The camera head of present embodiment pattern comprises lens barrel, imaging apparatus and is used to keep the device body of lens barrel, described lens barrel has zoom lens and lens holding cylinder, described zoom lens are arranged in described lens holding cylinder inside, and described imaging apparatus is used for converting the optical imagery that described zoom lens form to electric signal.
Zoom lens in the camera head of present embodiment pattern are constructed as follows.That is, aperture moves along optical axis direction in the zoom process; Aperture is positioned at object side with respect to aperture in the position of wide-angle side in the position of telescope end; Control the opening size of aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from wide-angle side to specific middle focal length; In scope, the opening size of aperture is made approximate definite value, to change the open F value from telescope end to specific middle focal length; And the specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4... (1)
In this camera head, preferably, preferably control the opening size of aperture in company with zoom operation, so that for example becoming in the scope from wide-angle side to specific middle focal length, the open F value falls into ± approximate definite value in 10% scope.
In addition, in this camera head, preferably, in scope, the opening size of aperture for example made fall into ± approximate definite value in 10% scope, to change the open F value from specific middle focal length to telescope end.
For above conditional (1),, make the control of the opening size of aperture is switched to the state of maximum gauge for approximate definite value from the open F value for the state of approximate definite value according to specific middle focal length.When exceeding down in limited time, specification becomes the specification specification much at one with existing popular standard zoom lens.On the other hand, when exceeding in limited time, aperture becomes excessive at the opening size of telescope end, and this causes size to become big and is difficult to revise aberration.
As mentioned above, in this camera head, the opening size of aperture changes in company with zoom operation, so that the open F value becomes approximate definite value in the given area of wide-angle side.Therefore, can satisfy the so-called high type specification of the zoom of guaranteeing given bright open F value simultaneously and being scheduled to.
In addition, increase and the side of looking in the distance that causes the size of lens barrel to increase, the opening size of aperture is made approximate definite value, thereby can realize avoiding increasing the size of lens barrel at the opening size of aperture.In addition, because telescope end does not need bright open F value, become big in image-side with respect to aperture so prevented the effective diameter of lens.Thereby prevented that too much light quantity from unnecessarily inciding the wide-angle side, thereby can carry out gratifying aberration correction.
Therefore, in this lens barrel, can make zoom area and high magnificationization compatible each other with bright open F value.
Embodiment according to camera head of the present invention below will be described.
At first, will be with reference to the structure of figure 5-9 description according to the element of the embodiment of camera head of the present invention.In the present embodiment, camera head is applied to digital still life camera.
As shown in Figure 5, camera head 20 comprises device body 21 and the lens barrel 22 that is maintained in the device body 21.
Lens barrel 22 is the interchangeable lenses that are releasably attached to device body 21.Therefore yet lens barrel 22 is in no way limited to interchangeable lenses, also can adopt the lens component that is installed in advance in the device body 21 or is provided with integratedly with device body 21.
Device body 21 portion within it has the control circuit (not shown).For example, control circuit carries out such as various processing such as signal Processing, recoding/reproduction processing, display process, read/write process and control and treatment.In this case: in described signal Processing, the picture signal that operations such as shooting obtain is carried out analog-digital conversion; In described recoding/reproduction was handled, picture signal was recorded/reproduces; In described display process, based on picture signal display image etc.In addition, in described read/write process, picture signal is written into/reads; In described control and treatment, control is to being arranged on the driving of the zoom lens 1 in the lens barrel 22.
In camera head 20, use conducts such as charge-coupled device (CCD), complementary metal oxide semiconductor (CMOS) (CMOS) device to have the imaging apparatus of imaging region 3.
Lens barrel 22 has lens holding cylinder 23 and is arranged in the above-mentioned zoom lens 1 of lens holding cylinder 23 inside.Lens holding cylinder 23 is provided with for user's rotary manipulation to carry out the zoom ring 23a of zoom.
Lens barrel 22 inside are provided with the aperture control gear 24 (with reference to figure 6) of controlling the opening size of aperture 2 in company with the zoom operation of zoom lens 1.
Aperture control gear 24 comprises installation unit 25 and aperture unit 26.
Installation unit 25 is the unit that are used for lens barrel 22 is installed to device body 21, and is installed to the end (rearward end) of the object side of lens holding cylinder 23.Installation unit 25 has carrying cylinder 27 and default ring 28.In this case, carrying cylinder 27 forms the sub-circular shape.In addition, to be supported tube 27 rotatably mounted for default ring 28.
Forming round-shaped patchhole 27a is formed on the rear surface of carrying cylinder 27 (with reference to figure 7).
Default ring 28 has the portion that is supported 29 of the annular shape of forming and is supported roughly outstanding forward guide protrusion portion 30 (with reference to figure 8) of portion 29 from this.
Be supported portion 29 and be provided with rearwardly projecting connection (coupling) projection 29a.Attachment tabs 29a gives prominence to (with reference to figure 7) backward from the patchhole 27a of carrying cylinder 27.Be supported portion 29 and pushed away (urge) direction to circumferencial direction by the spring member (not shown).
Guide protrusion portion 30 is made of base end part 30a, pars intermedia 30b and head 30c.In this case, base end part 30a extends front and back continuously from being supported portion 29.Pars intermedia 30b extends into respect to base end part 30a from the front end of base end part 30a continuously.In addition, head 30c extends front and back continuously from the front end of pars intermedia 30b.
As shown in Figure 9, aperture unit 26 by support base 31, be directed base portion 32 and a plurality of aperture blades 33,33 ... constitute.In this case, support base 31 forms the sub-circular shape.Be directed base portion 32 and form the sub-circular shape, and it is rotatably mounted to be supported base portion 31.In addition, a plurality of aperture blades 33,33 ... be can be rotated to support on support base 31 and be directed between the base portion 32.In addition, a plurality of aperture blades 33,33 ... play the function of said aperture 2.
A plurality of support holes 31a, 31a ... in support base 31, form along circumferentially being separated from each other.
Outwards outstanding separately a pair of jut 32a, the 32a of being directed is arranged on the peripheral surface that is directed base portion 32.A plurality of cam hole 32b, 32b ... in support base 31, form along circumferentially being separated from each other.
Aperture blades 33 has outstanding forward fulcrum post 33a and rearwardly projecting cam pin 33b.In aperture blades 33, it is rotatably mounted that fulcrum post 33a is supported the support holes 31a of base portion 31, supported slidably and cam pin 33b is directed the cam hole 32b of base portion 32.Therefore, when be directed base portion 32 with respect to support base 31 when circumferential direction is rotated, cam pin 33b, 33b ... cam hole 32b, 32b ... in the position be changed.Therefore, aperture blades 33,33 ... with fulcrum post 33a, 33a ... for fulcrum with respect to support base 31 be directed base portion 32 and pivot, thereby change opening diameter 33c by aperture blades 33,33 ... the size that limits.
In aperture unit 26, support base 31 is installed to the mobile frame (not shown) that keeps the 3rd lens combination 13 by screw element 100,100 is installed.Therefore, aperture unit 26 and the 3rd lens combination 13 move along optical axis direction integratedly.
In aperture unit 26, be directed jut 32a, the 32a that are directed base portion 32 engage slidably with guide protrusion portion 30 in the default ring 28 that is arranged on installation unit 25.Therefore, when aperture unit 26 and the 3rd lens combination 13 integratedly when optical axis direction moves, being directed base portion 32 can be according to being directed jut 32a, the 32a bonding station with respect to guide protrusion portion 30, and with respect to support base 31 rotations.
Under the state before lens barrel 22 is installed to device body 21, in the default ring 28 of installation unit 25, attachment tabs 29a is kept at one end (with reference to figure 7) by the thrust of spring member.Therefore, by aperture blades 33,33 ... the opening size 33c that limits is reduced, so that the state that significantly blocks zoom lens 1 to be provided.
When lens barrel 22 was installed to device body 21, the bar (not shown) that attachment tabs 29a is set in the device body 21 was pressed, and default ring 28 overcomes the thrust of spring member and rotates.When default ring 28 rotates, being directed base portion 32 and presetting ring 28 rotations with what guide protrusion portion 30 engaged.Therefore, by aperture blades 33,33 ... the opening size 33c that limits becomes big, so that the aperture release conditions to be provided.
In wide-angle side, be directed jut 32a, 32a and engage with the rearward end of the pars intermedia 30b of guide protrusion portion 30.Under the wide-angle side state, the open F value is set at F2.8 approximately.At this moment, by aperture blades 33,33 ... it is the aperture area that the circle of 15.274mm equates that the opening size 33c that limits for example has with diameter.
In zoom lens 1, for example, when carrying out zoom operation from wide-angle side towards telescope end, first to the 4th lens combination 11-14 moves along optical axis direction, the interval of winning between the lens combination 11 and second lens combination 12 is increased, interval between second lens combination 12 and the 3rd lens combination 13 narrows down, and the interval between the 3rd lens combination 13 and the 4th lens combination 14 narrows down.At this moment, aperture unit 26 and the 3rd lens combination 13 move along optical axis direction (forward) each other integratedly.
When aperture unit 26 from the wide-angle side state when optical axis direction moves because be directed the pars intermedia 30b that jut 32a, 32a are directed to guide protrusion portion 30, rotate along circumferential direction with respect to support base 31 so be directed base portion 32.Therefore, by aperture blades 33,33 ... the opening size that limits is along with aperture unit 26 moving and become big forward.At this moment, the open F value remains the promptly about F2.8 of definite value.Be directed under the state that jut 32a, the 32a front end with the pars intermedia 30b of guide protrusion portion 30 engages, by aperture blades 33,33 ... it is the aperture area that the circle of 19.702mm equates that the opening size 33c that limits for example has with diameter.
When further when telescope end carries out zoom operation, aperture unit 26 and the 3rd lens combination 13 move along optical axis direction (forward) each other integratedly, thereby will be directed the head 30c that jut 32a, 32a guide to guide protrusion portion 30.Therefore, be directed base portion 32 with respect to support base 31 rotation, therefore by aperture blades 33,33 ... the opening size 33c that limits remains given size.At this moment, the open F value increases and deepening gradually from about F2.8, and obtains the maximal value that is about F3.5.
It should be noted, for the brightness of wide-angle side, because the factors such as miniaturization of the screen size of imaging apparatus, so also the open F value can be remained for example definite value of about F2.
In addition, though described the mechanism that is used to control aperture 2 as an example by providing mechanical mechanism, the mechanism that is used to control aperture 2 is in no way limited to mechanical mechanism.For example, also can use the aperture control gear that does not have machine power to transmit that utilizes Electromagnetic Drive.
Though camera head is applied to digital still life camera in the above-mentioned embodiment, the range of application of camera head is in no way limited to digital still life camera.That is, the camera head camera section that also can be applicable to digital video camera usually, the mobile phone of camera is housed and the digital input-output units such as PDA(Personal Digital Assistant) of camera are housed is graded.
All only for implementing illustrative example of the present invention, therefore technical scope of the present invention is explained on the property of should in no way limit ground for the shape of the each several part shown in the above-mentioned embodiment and numerical value.
The application comprises the related theme of submitting in Jap.P. office on July 25th, 2008 of Japanese priority patent application JP 2008-192364, and its full content is incorporated this paper by reference into.

Claims (7)

1. zoom lens, wherein:
Aperture moves along optical axis direction in the zoom process;
Described aperture is positioned at object side with respect to described aperture in the position of wide-angle side in the position of telescope end;
Control the opening size of described aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from described wide-angle side to specific middle focal length;
From described specific middle focal length in the scope of described telescope end, the opening size of described aperture is made approximate definite value, to change described open F value; And
The described specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4 ... (1).
2. zoom lens as claimed in claim 1 wherein, in the scope from described wide-angle side to described specific middle focal length, make the open F value brighter than F3.
3. zoom lens as claimed in claim 1, wherein:
Described zoom lens by first lens combination with positive refracting power of arranging successively, second lens combination with negative refracting power from object side, have positive refracting power and the 3rd lens combination that moves along optical axis direction integratedly with described aperture and the 4th lens combination with positive refracting power constitute;
When the side of looking in the distance from wide angle side is carried out zoom operation, interval between described first lens combination and described second lens combination increases, interval between described second lens combination and described the 3rd lens combination narrows down, and the interval between described the 3rd lens combination and described the 4th lens combination narrows down;
In the focusing process, described second lens combination moves along optical axis direction; And
Zoom is set at 3.5 times or bigger.
4. zoom lens as claimed in claim 3, wherein, described second lens combination has at least three concavees lens and a slice convex lens, and the concavees lens of close object side and at least one surface in the described convex lens form aspheric surface.
5. zoom lens as claimed in claim 3, wherein:
By arranging successively that from object side concavees lens, convex lens and male bend moon-shaped lens constitute described first lens combination;
By arranging successively that from object side following lens constitute described second lens combination: at least one surface forms aspheric recessed meniscus shaped lens; Concavees lens; Surface by concavees lens and image-side forms the balsaming lens that aspheric convex lens form; Recessed meniscus shaped lens with concave surface directed towards object side;
Described aperture is arranged in the object side of described the 3rd lens combination;
Biconvex lens and the balsaming lens that forms by biconvex lens and concavees lens constitute described the 3rd lens combination by arranging successively from object side; And
By arranging successively that from object side at least one surface forms aspheric biconvex lens, concave surface points to the recessed meniscus shaped lens of image-side and the balsaming lens that is formed by concavees lens and convex lens, constitute described the 4th lens combination.
6. lens barrel comprises:
Zoom lens; With
Portion is furnished with the lens holding cylinder of described zoom lens within it;
Wherein, in described zoom lens:
Aperture moves along optical axis direction in the zoom process;
Described aperture is positioned at object side with respect to described aperture in the position of wide-angle side in the position of telescope end;
Control the opening size of described aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from described wide-angle side to specific middle focal length;
From described specific middle focal length in the scope of described telescope end, the opening size of described aperture is made approximate definite value, to change described open F value; And
The described specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4 ... (1).
7. camera head comprises:
Lens barrel, described lens barrel has zoom lens and lens holding cylinder, and described zoom lens are arranged in described lens holding cylinder inside;
The optical imagery of described zoom lens formation is converted to the imaging apparatus of electric signal; With
Be used to keep the device body of described lens barrel;
Wherein, in described zoom lens:
Aperture moves along optical axis direction in the zoom process;
Described aperture is positioned at object side with respect to described aperture in the position of wide-angle side in the position of telescope end;
Control the opening size of described aperture in company with zoom operation, so that the open F value becomes approximate definite value in the scope from described wide-angle side to specific middle focal length;
From described specific middle focal length in the scope of described telescope end, the opening size of described aperture is made approximate definite value, to change described open F value; And
The described specific middle focal length formula (1) that meets the following conditions:
Wide-angle side focal length * 1.5<specific middle focal length<telescope end focal length/1.4 ... (1).
CN2009101646960A 2008-07-25 2009-07-27 Zoom lens, lens barrel and image pickup apparatus Expired - Fee Related CN101634743B (en)

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